| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| OisÍN | OSH-een, USH-een | Irish, Irish Mythology | ||
| Oscar | AHS-kər (English) | English, Irish, Portuguese (Brazilian), Italian, Swedish, Norwegian, Danish, Dutch, French, Irish My | ||
| ParthalÁN | PAHR-ha-lawn | Irish Mythology | ||
| RÍGhnach | - | Irish Mythology | ||
| RÍOghnach | - | Irish Mythology | ||
| Sabia | - | Irish Mythology | ||
| Sadb | SIEV (Irish) | Irish, Irish Mythology | ||
| Sadbh | SIEV (Irish) | Irish, Irish Mythology | ||
| Sadhbh | SIEV (Irish) | Irish, Irish Mythology | ||
| Sionann | - | Irish Mythology |